When I used Xtol and D76 in Alaska, I always mixed with tap water - and got the same white particles (the crud / floaters) that you get! I never thought back then to mix with any kind of "special" water. Hehe...guess I was too young to think about things like that at the time.
But - it always worked. So, I don't think the particles are really your problem. It's probably the soda bottles. At the time I used dark brown plastic jugs from B&H, and they worked pretty well - kept for at least 4 months, but I always wanted glass.
I'd say try some glass bottles and "special water" if you want maximum longevity! I know you want Xtol specifically, and I don't blame you because it's fabulous stuff, but you could try some HC-110 syrup if you shoot very little and just need a developer around all the time. That stuff's supposed to last forever!